Question

I am having a problem with an Android program I’m working on. The method below is in MyActivity. MyActivity has an inner class InnerClass which extends AsyncTask. In the doInBackground method of InnerClass i search a database. The result of that search is passed to this method processSearchResult. Everything works except the very last line throws a NullPointerException. I tried using getApplicationContext() in place of this while creating the button and it still threw the exception. I debugged it and found the problem is in the android.content.ContextWrapper class. In the getApplicationContext() method is a call mBase.getApplicationContext. The problem is that the variable mBase is null. When using the this keyword there is still a call to this method and mBase is still null. Can anyone tell me why mBase is null? Or if its actually normal for mBase to be null?

public void processSearchResult(ResultSet result) {
    try {

    int x = 1;
    while (result.next()) {

        String name = result.getString(1);
        String ing = result.getString(2);
        String ins = result.getString(3);
        String notes = result.getString(4);
        String type = result.getString(5);
        String course = result.getString(6);

        Recipe r = new Recipe(name, ing, ins, notes, type, course);
        recipeList.add(r);

        Button button = new Button(this);

Answer 1

You can’t update the user interface from the doInBackground method of the AsyncTask you need to publishProgress and update it from the onProgressUpdate method instead.

How do I publish my progress from doInBackground

publishProgress(0); //Assuming progress is 0

Where do I update the UI from then?

@Override
protected void onProgressUpdate(Integer... progress){
    //HERE
}

this may not refer to what you’re thinking.
What I do is keep a private global Context variable in my code for future reference as in:

private Context x = this;